<?php
$data = array(1 => 'val1', array(2 => 'val2', array(3 => 'val3')), 4 => 'val4');
$iterator = new RecursiveIteratorIterator(new RecursiveArrayIterator($data));
foreach ($iterator as $foo) {
$key = $iterator->key();
echo "update {$key}\n";
var_dump($iterator->getInnerIterator());
$iterator->offsetSet($key, 'alter');
var_dump($iterator->getInnerIterator());
}
$copy = $iterator->getArrayCopy();
var_dump($copy);